Method for detecting and measuring foam forming compounds in aqueous solutions

ABSTRACT

A method for detecting change in the foam forming characteristic of an input stream of an aqueous solution which continuously samples the input stream by taking a series of discrete, independent measurements. The method relies on an acoustic sensor to measure foam height within a column. A sample of the input stream is introduced into the column, and aerated to produce foam. The height of the column of foam is then measured using the acoustic sensor, which is correlated with the concentration of foam forming chemical.

This application is a continuation-in-part of U.S. patent applicationSer. No. 09/917,565, filed Jul. 25, 2001, now U.S. Pat. No. 6,405,580,which is a continuation-in-part of patent application Ser. No.09/566,888, filed May 08, 2000, now U.S. Pat. No. 6,397,665.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a method for detecting thepresence of foam forming compounds in aqueous solutions. Moreparticularly, the present invention relates to a method which detectsthe presence of specific foam forming compounds in an aqueous solution,and, when calibrated, measures the concentration of the foam formingcompounds present in the aqueous solution.

2. Description of the Prior Art

Foam forming compounds include cleaning compounds, such as detergents,fire-fighting chemicals, and naturally occurring surfactants, such asplant extractives. The presence of foam forming compounds can interferewith the operation of chemical plants, such as wastewater treatmentplants, by causing inaccurate readings in flow and level sensingdevices.

Foaming of wastewater tends to lift solid materials out of the liquidphase and suspend the materials in the foam. These solid materials mayinclude metals or other hazardous materials. In open top tanks,pollutant-laden foams may be blown off the surface of the wastewater andonto the surrounding property. Hazards of this type often result incitations from public health offices and environmental protectionofficials.

Some foam forming chemical are also toxic to the microorganisms used inwastewater treatment plants. Early detection of foam forming chemicalspermits process streams contaminated with these chemicals to be divertedfrom the main process flow. The diverted flow can be subsequentlytreated in a specialized foam forming agent removal process.

Foam detecting devices used in the past to detect the presence of foamforming chemicals in an aqueous solution cannot rapidly detect a changeof state from a foaming input stream to a non-foaming input stream. Forexample, if a prior art device was measuring the foam formingcharacteristic of an input stream that contained a high concentration ofa foam forming chemical, and then the input stream was changed to astream that contained little or no foam forming chemical, the prior artdevice could not rapidly detect the change in input stream composition.This is because the prior art device has a fixed or static solutionreservoir at the bottom of the device, and the concentration of the foamforming chemical in that reservoir is changed only by dilution from theinput stream. It may take several minutes before a low concentrationinput stream dilutes the solution in the reservoir to a concentrationthat no longer forms a significant amount of foam.

Devices used in the past to detect the presence of foam formingchemicals are generally not automated. These devices are manuallyoperated and are best suited to a laboratory environment.

Prior art devices for detecting the presence of foam forming chemicalsare also fragile, generally consisting of a piece of custom blownglasswork.

In addition, prior art devices rely on photo-optical sensor pairs todetect and measure the presence of foam at discrete locations. Thisapproach is expensive to implement and provides a limited number of foamheight detection values. Also, reliance upon photo-optical pairs todetect the present of foam requires that the column containing the foambe transparent. In some foam sensing applications, a film of oil, algae,bacteria, and other deposits may eventually occlude a clear column. Thisrenders the photo-optical sensors inoperable.

Further, at low concentrations of foam forming chemical, the foam canusually be characterized as being composed of a small number of largebubbles. The beam from a photo-optical sensor can intermittently passthrough such loosely structured foam, resulting in intermittent falsereadings of foam height.

Accordingly, there is a need for an apparatus for detecting andmeasuring foam forming compounds in aqueous solutions which is accurate,relatively simple in design, and sufficiently strong to avoid breakageand low cost.

SUMMARY OF THE INVENTION

A sample of the liquid or wastewater to be tested enters a verticallypositioned tubular column from a fill valve through a column cap at thetop of the tubular column, flows down the sides of the column, andcollects in a lower portion of the column. The liquid level in thecolumn rises to a liquid level switch. Closing the liquid level switchprevents further flow of liquid into the tubular column.

After a sample of liquid has collected in the lower portion of thecolumn, an air pump is actuated and compressed air flows into the samplethrough an aeration stone. The air bubbles produced by the aerationstone cause the foam forming compounds in the sample to produce foam.The foam rises in the column and lifts a float which functions as asolid target for an acoustic distance measuring device. The measuringdevice measures height within the column, generating a continuous analogelectrical output signal which is a function of foam height. The valueof voltage produced by the measuring device is measured and retained bya programmable logic controller connected to the measuring device.

As the float rises in the sensor tube, a beam of light betweenphoto-optical sensors is encountered and is broken. As the float passesthe beam of light, the beam then encounters the foam in the tubularcolumn. If the foam is of sufficient density that it continues tointerrupt the beam of light and it continues to lift the ball to a lowerset point programmed into the measuring device, a red indicator light isilluminated. If the foam density is insufficient to block the beam oflight generated by the optical sensors, the red indicator light does notilluminate and the system recognizes that the aqueous foam forming filmconcentration is below a predetermined threshold level. When the redindicator light remains illuminated, it indicates that the samplesolution contains aqueous foam forming film at or above a predeterminedthreshold and the apparatus automatically sends a message to alert theuser.

After a foam height measurement has been made, the fill valve closes, asample drain valve opens, and a 3-way valve is positioned to divertcompressed air from the aeration stone to the top of the column. Thisforces the sample of solution and foam from the column through a drainvalve. After the solution has been drained from the column, the fillvalve opens, the drain valve closes, air is re-directed to the aerationstone, and the entire sample acquisition and measurement cycle isrepeated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an apparatus for detecting and measuring foamforming compounds in aqueous solutions comprising the present invention;

FIGS. 2A-2C is an electrical schematic diagram of the 120 VAC controlcircuity for the apparatus of FIG. 1; and

FIGS. 3A-3F is an electrical schematic diagram which illustrates therelay logic circuitry for the programmable logic controller of theapparatus of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first to FIG. 1, there is shown an apparatus, designatedgenerally by the reference numeral 20, which detects the presence offoam forming compounds in aqueous solutions. Apparatus 20, whencalibrated also will measure the concentration of specific foam formingcompounds in an aqueous solution. Foam forming compounds includecleaning compounds such as detergents, fire fighting chemicals, andnaturally occurring surfactants such as plant extractives.

The apparatus 20 comprising the present invention, operates by measuringthe foam forming capability of an aqueous solutions with a time seriesof discrete tests. A sample of an aqueous solution is introduced intoapparatus 20. The height of the column of foam is then measured by anapparatus 20 using an acoustic distance-measuring device. The sample ofthe aqueous solution is then discarded and the sampling process isrepeated using apparatus 20. The height of the column of foam iscorrelated with the concentration of foam forming chemical. Theapparatus is capable of detecting fewer than fifteen parts per millionof aqueous film forming foam in less than forty-five seconds.

A sample of a liquid or aqueous solutions to be tested enters apparatus20 through an inlet supply line 24 (as indicated by arrow 22) whichincludes an electrically operated supply/fill valve 26. When valve 26 iselectrically energized, fill valve 26 is opened such that the liquid topass through water supply line 27 and an opening 29 at the top of atubular column 30 through a column cap 31 into the tubular column 30.The liquid then flows down the inner wall/sides 35 of tubular column 30,and collects in the bottom or lower portion 32 of tubular column 30.

The liquid level in the lower portion 32 of column 30 rises to the levelof a liquid level switch 34. When liquid level switch 34 closes, fillvalve 26 is deactivated and the flow of liquid is through fill valve 26to a drain located on the backside of foam sensor housing 36.

When the sample of the liquid has collected in the lower portion 32 oftubular column 30, an electrically operated air pump 44 is actuatedproviding compressed air which flows through an air supply line 46 intoa three-way electrically operated air valve 48. The compressed air thenpasses through air valve 48 and an air line 50 into the liquid samplethrough a porous aeration stone 52 which forms bubbles. The aerationstone 52 is mounted horizontally in the lower portion 32 of tubularcolumn 30 50 that it generates small air bubbles within the sample.

The many small air bubbles generated by aeration stone 52 cause the foamforming compounds in the sample to produce foam. The foam rises intubular column 30 lifting a spherical-shaped lightweight float/target 66into the upper portion 54 of tubular column 30. Spherical-shapedlightweight float/target 66 comprises a polystyrene ball.

As depicted in FIG. 1, the upper portion 54 of tubular column 30 islarger in diameter than the lower portion 32 of tubular column 30.Between the upper portion 54 and the lower portion 32 of tubular column30 is a reducing collar 56. When apparatus 20 is not operational, float66 rest within the reducing collar 56 of tubular column 30. Reducingcollar 56 has a centrally located opening 70 which allows foam to passthrough opening 70 to the upper portion of tubular column 30 liftingfloat 66 in a vertical direction upward within the upper portion 54 oftubular column 30.

The float 66 serves as a solid target for an acoustic distance measuringdevice/acoustic sensor 67. The acoustic distance measuring device 67,which is positioned at the top of tubular column 30, measures the heightof the column of foam within tubular column 30 by bouncing ultrasonicsound waves off the target 66 and measuring time of travel of theultrasonic waves to and from the target 66. The acoustic distancemeasuring device 67 produces a continuous analog electrical outputsignal which is a function of foam height within tubular column 30. Theoutput signal's voltage value produced by the acoustic distancemeasuring device 67 is measured, sampled and retained by asample-and-hold circuit within a programmable logic controller 69connected to measuring device 67, as shown in FIG. 2A.

The programmable logic controller 69 used in the preferred embodiment isa Model Micro³ Programmable Logic Controller commercially available fromIDEC Corporation of San Jose, Calif. Programmable logic controller 69 isprogrammed using WINDLER software which is commercially available fromIDEC Corporation. The WINDLER software includes a monitor mode whichallows the user to monitor the logic control program currently runningin the programmable logic controller in real time.

At this time it should be noted that a laser distance measuring devicecould be substituted for the acoustic distance measuring device 67 toperform the function of measuring the height of the foam column withintubular column 30.

It should also be noted that the acoustic distance measuring device usedin the present invention is a Model M-5000 Smart Ultrasonic Sensorcommercially available from Massa Products Corporation of Hingham, Mass.The Current Loop Output Settings for device are as follows: 0 mAdistance is 13 inches, the 20 mA distance is 4.5 inches and the outputspan is 0-20 mA. The Set point Output Settings are as follows: the closeset point distance is 7 inches and the far set point distance is 9inches. The software for the M-5000 Smart Ultrasonic Sensor allows theuser to monitor the performance of the sensor in real time. A statuspanel which appears on an external computer screen indicates the realtime distance from the ultrasonic sensor to the target.

If float 66 rises above a predetermined set point within the portion 54of tubular column 30, an alarm is activated. The alarm that is activatedcomprises a red indicator light 71, shown in FIG. 2A.

After a foam height measurement within tubular column 30 has been made,an electrically operated sample drain valve 60 opens (i.e. isdeactivated) and the sample drains from column 30 through valve 60 and adrain pipe 62 (as indicated by arrow 64).

Simultaneously, with the opening of valve 60, valve 48 is deactivatedwhich diverts compressed air provided by air pump 44 through an airsupply line 47 to an opening positioned within the upper portion 54 oftubular column 30. The opening 68 is positioned immediately below columncap 31 within tubular column 30. Compressed air supplied through opening68 forces the sample and foam out of tubular column 30 through drainvalve 62 and drain pipe 64.

After the foam forming solution has been drained from tubular column 30,valve 60 is activated or closed, valve 26 is again activated and thesample acquisition cycle is repeated.

There is also mounted within foam sensor housing 36 a pair ofphoto-optical sensors 77 and 79 which are in alignment on opposite sidesof the upper portion 54 of tubular column 30. The pair of photo-opticalsensors 77 and 79 allow an operator of apparatus 20 to obtainsupplementary measurements of foam density within tubular column 30.When the foam within tubular column 30 has a low density, that is thefoam consists of a few large bubbles, the beam of light from thetransmitter of the pair of photo-optical sensors 77 and 79 will passthrough the foam to the receiver of the pair of photo-optical sensors 77and 79.

When, however, the foam within tubular column 30 has a high density,that is the foam consists of many small bubbles, the beam of light fromthe transmitter of the pair of photo-optical sensors 77 and 79 will notpass through the foam to the receiver of the pair of photo-opticalsensors 77 and 79. The data provided by the pair of photo-opticalsensors 77 and 79 relative to foam density is then combined with datafrom acoustic distance measuring device 67 to provide an accurate andreliable measurement of foam quality. The data provided by opticalsensor 79 to programmable logic controller 69 is in the form of a directcurrent voltage signal.

Referring to FIGS. 1 and 2A-2C, programmable logic controller 69controls the operation of apparatus 20. A power on switch SW1 when setto the ON position supplies 120 VAC through fuse 3A to programmablelogic controller 69. Programmable logic controller 69, in turn, supplies24 VDC to transmitter 77 and receiver 79 illustrated in FIG. 2B.Acoustic distance measuring device 67 and photo-optical receiver 79 areconnected to programmable logic controller 69 to provide electricalsignals to controller 69 indicative of foam quality in the upper portion54 of tubular column 30.

Programmable logic controller 69 provides electrical signals to coilsC₀, C₁, C₂ and C₃ to activate coils. When, for example, coil C₀ isenergized, contacts R_(0A) and R_(0B) are closed. This activates airpump 44 and a sample pump 80 which is used to supply samples of theliquid to apparatus 20 for testing for the presence of foam in thesamples.

When programmable logic controller 69 energizes coil C₁, contact R_(1A)closes activating light 73. Similarly, when programmable logiccontroller 69 energizes coil C₂, contact R_(2A) closes activating light71. Energizing coil C₃ closes contact R_(3A) which activates an externalsump pump 82. Programmable logic controller 69 also provides activationsignals to solenoid S₀, solenoid S₁, and solenoid S₂. Solenoid S₀ is thesolenoid for supply valve 26, solenoid S₁ is the solenoid for air valve48, and solenoid S₂ is the solenoid for drain valve 60.

Referring to FIG. 1, there is shown an oil water separator 84 whichsupplies water samples to apparatus 20 via inlet supply line 24 andelectrically operated supply valve 26. The oil water separator 84comprises an inlet line 85 which includes a shut off valve 91 and a flowdirection sensing switch SW2; a backwash strainer 86 for removing largeparticulate matter; and a filter 88 equipped with an oleophilic element.The oil water separator 84 also has a pair of pressure gauges 95 and 96and a pressure gauge 98 operatively coupled to the backwash strainer 86.

The filter 88 removes oil from the water samples. Oil water separator 84also includes a backwash valve 90 which has a solenoid 53 connected toprogrammable logic controller 69. Periodically reversing the water flowthrough backwash strainer 86 is required to clean strainer 86. Thebackwash interval and duration is controlled by programmable logiccontroller 69 which energizes the solenoid S3 of backwash valve 90 toclean backwash strainer 86. Activation of maintenance alarm 83 requireclosure of contact R_(1B) which is illustrated in FIG. 2C.

The oleophilic element of filter 88 will eventually plug up and have tobe replaced. A plugged filter results in an increase in pressure dropacross filter 88. When this occurs, a differential pressure switch SW4sends an electrical signal to programmable logic controller 69indicating that the oleophilic element of filter 88 needs replacement.Apparatus 20 is designed to automatically shut down and alert the userof apparatus that the oleophilic element of filter 88 needs replacement.The illumination of amber lamp 73 indicates that maintenance isrequired.

Referring to FIGS. 1 and 2A, electrical signals for a sump pump 82 andbackwash valve 90 are provided by programmable logic controller 69. Thesump pump 82 is connected to a holding tank 94 via a fluid flow line 81.Holding tank 94 has mounted thereon an upper float switch SW5 and alower float switch SW6. The holding tank 94 is connected via a T-shapedpipe connector 63 to drain pipe 62 to receive the samples of the aqueoussolution, i.e. wastewater being tested. Backwash valve 90 is alsoconnected to holding tank 94 via connector 63.

When the holding tank 94 is full switch SW5 closes sending a signal toprogrammable logic controller 69 which turns on sump pump 82. When theliquid level in holding tank 94 reaches a low water level switch SW6closes sending a signal to programmable logic controller 69 which turnsoff sump pump 82.

While apparatus 20 is operational, many different events can occur. Thesequence of events during normal operation of the apparatus 20 areillustrated by the following example. Bilge water is pumped from a shipto an oily-waste lift station. Assume for this example that thewastewater contains 50 ppm Aqueous Foam Forming Film (AFFF). As the sumpin the lift station fills, large wastewater transfer pumps are energizedto move the wastewater from a collection point to a wastewater treatmentplant.

A small portion or sample of the waste stream is diverted to theapparatus 20. Flow direction sensing switch SW2 installed in the oilwater separator 84 signals apparatus 20 to begin the wastewater samplingprocess. Fluid direction sensing switch SW2 is adapted to detect theflow of liquid through separator 84. Fluid direction sensing switch SW2is connected to programmable logic controller 69.

The programmable logic controller 69 continuously loops through its setof instructions. Therefore, controller 69 is not necessarily at thebeginning of the program cycle when the apparatus 20 receives the signalfrom the flow direction sensing switch SW2. However, for this example wewill assume the apparatus 20 starts at the beginning of a fill cycle.

With the fill valve 26 energized, flow is directed to the top of thetubular column 30. The sample flows into the cap 31 on the top of thetubular column 30 and runs down the wall of the tubular column 30. Waterfills the chamber formed within the bottom portion 32 of the tubularcolumn 30 until the liquid level switch 34 in the chamber closes. Whenthe chamber is full, fill valve 26 is de-energized and the wastewaterflow is bypassed to the sump/holding tank 94 through valve 90 which isconnected to sump 94.

After an initial delay (to flush the pipes of the previous sample ofwastewater), the air pump 44 is activated and air flows through the airvalve 48 to the aeration stone 52. Aeration occurs for a predeterminedlength of time and foam is generated in the tubular column 30. As thefoam rises in the tubular column 30, the foam lifts a polystyrene ball66. The ball 66 provides a firm target for acoustic distance measuringdevice 67, which measures the distance to the target ball 66. Becausethe wastewater sample contains 50 ppm AFFF, sufficient foam will begenerated in the column for the target 66 to reach a sensor set point.

As the target 66 rises in the sensor tube, the beam of light betweenphoto-optical sensors 77 and 79 is broken. As the target 66 passes thebeam, the beam then encounters the foam in the tubular column 30. If thefoam is of sufficient density that it continues to interrupt the beam oflight and it continues to lift the ball to a lower set point programmedinto the acoustic sensor 67, red indicator light 71 is illuminated. Ifthe foam density is insufficient to block the beam from the opticalsensors 77 and 79, the red indicator light 71 does not illuminate, andthe system recognizes that the AFFF concentration is below apredetermined threshold level. When the red indicator light 71 isilluminated, it indicates that the sample solution contains AFFF at orabove a predetermined threshold and apparatus 20 automatically sends amessage to alert the user which may be, for example a plant operator. Assoon as the red indicator light 71 is illuminated, an internal timer inthe control program for programmable logic controller 69 begins a countdown. The target 66 must reach the lower set point during the nextsample cycle before the timer expires or the red indicator light 71 willgo out. If the ball continues to rise to a second high alarm programmedinto the acoustic sensor 67, air is diverted from the aeration stone 52to the top of the tubular column through opening 68. This prevents thetarget and foam from rising further and contacting the acoustic sensor67.

After a predetermined length of time, the apparatus 20 enters awash-down cycle. The drain valve 60 is opened, sample flow is redirectedto the top of the tubular column 30, and air is redirected from theaeration stone 52 to the top of the column 30 through opening 68. Thesample is flushed out the drain valve 60 in the bottom of the tubularcolumn 30 and flows into the sump 94. Air pressure in the top of thecolumn 30 helps expel the sample from apparatus 20. When the wash-downcycle is finished, the drain valve 60 closes and a new wastewater samplefills tubular column 30.

This process is repeated until the sample no longer contains a highenough concentration of AFFF in the wastewater to cause the target 66 toreach the low set point before the internal timer within programmablelogic controller 69 expires. When this occurs, the red indicator light71 no longer illuminates and a message is sent via an SCADA systeminterface that the foam event has ended.

The SCADA system (Supervisory Control and Data Acquisition) reports thepresence of AFFF foam in the wastewater to a central monitoringfacility, such as the wastewater treatment plant.

The foam concentration measuring process performed by apparatus 20 willalso stop when the flow direction sensing switch SW2 signals theapparatus 20 that fluid flow is no longer present in the wastewatertransfer discharge line. When this occurs, the apparatus 20 isautomatically switched off.

Referring to FIGS. 3A-3F, there is shown a ladder logic diagram forprogrammable logic controller 69. The programmable logic controller 69activates and de-activates the mechanical and electrical elements ofapparatus 20. For example to activate the air pump 44, the flow switchSW2 must be closed and an initial line flush must occur closing flowswitch contact 10000 and initial line flush contact T009. This resultsin activation of Air Pump Relay Q0010 which turns on air pump 44. Theladder logic on Rungs 1, 2 and 3 must be activated to activate air pump44.

Rungs 4 and 5 turn on a maintenance alarm 83 if (1) there is a highfilter delta pressure for filter 88 (2) the optical path is obscured foroptical sensors 77 and 79.

Rungs 6 and 7 start aeration and blow down timers on the closure ofswitch 34. Rung 8 closes fill valve 26 if apparatus 20 is in an aerationcycle and opens the valve 26 for a blow down or maintenance alarm. Rung9 closes valve 48 during an aeration cycle and a bypass occurs during aninitial line flush and a maintenance alarm. Rung 10 closes valve 60during aeration. Rung 11 activates a blow down. Rung 12 delays theinputs from sensors 77 and 79 for a predetermined time period tominimize false signals.

Rungs 13 and 14 set foam alarm 87 when the float 66 is above a low setpoint and foam density is high. Activation of foam alarm 87 requiresclosure of contact R_(2B) which is illustrated in FIG. 2C. Rung 15 and16 reset foam alarm 87 when float 66 falls below a low set point, areset timer is started and float 66 fails to rise to the low set pointbefore the reset timer expires.

Rung 17 sets an internal relay if a high set point has been reached.Compressed air is diverted to the top of column

Rung 19 turns on sump pump 82 when upper float switch SW5 closes, whilerung 20 turns off sump pump 82 when lower float switch SW6 closes.

Rungs 21-24 are used to control a backwash process. Programmable logiccontroller 69 periodically actuates the solenoid S₃ of backwash valve90. Actuating the solenoid S₃ of backwash valve 90 results in wastewaterinflow being diverted through valve 90 washing off accumulated dirt andother solid particles from backwash strainer 86. The accumulated dirtand other solid particles then pass through backwash valve 90 intoholding tank 94 where the wastewater can be pumped to a drain using pump82.

The apparatus 20 is capable of detecting the presence of concentrationsof aqueous film forming foam in bilge water as low as fifteen parts permillion in approximately forty-five seconds.

From the foregoing, it may readily be seen that the present inventioncomprises a new, unique, and exceedingly useful system for detecting andmeasuring the concentration of foam forming compounds in aqueoussolutions which constitutes a considerable improvement over the knownprior art. Many modifications and variations of the present inventionare possible in light of the above teachings. It is to be understoodthat within the scope of the appended claims the invention may bepracticed otherwise than as specifically described.

What is claimed is:
 1. A method for detecting and measuring foam inwastewater, comprising the steps of: generating a plurality of controlsignals; introducing a sample of said wastewater through a fill valveinto a vertically positioned tubular column having an inner wall, afirst of said plurality of control signals opening said fill valve toallow said wastewater to pass through said fill valve into said tubularcolumn and flow down the inner wall of said tubular column to a lowerportion of said tubular column; generating a compressed gas, saidcompressed gas being generated by an electrically operated pumpactivated by a second of said plurality of control signals; providingsaid compressed gas through an air valve to an aeration stone positionedin the lower portion of said tubular column; generating air bubbleswithin said wastewater causing a formation of said foam within saidtubular column, said air bubbles being generated by air flow throughsaid aeration stone when said compressed gas, responsive to a third ofsaid plurality of control signals passes through said air valve to saidaeration stone; raising a spherical-shaped float positioned within saidtubular column in an upward direction within said tubular column, saidspherical-shaped float being raised within said tubular column by theformation of said foam within said tubular column; generating ultrasonicwaves, said ultrasonic waves being generated by an ultrasonic sensorpositioned at the top of said tubular column; measuring a time of travelfor said ultrasonic waves between said ultrasonic sensor and saidspherical-shaped float by bouncing said ultrasonic waves off of saidspherical-shaped float; generating an analog signal which is a functionof foam height within an upper portion of said tubular column, saidultrasonic sensor generating said analog signal in response tocontinuous measurement of the time of travel of said ultrasonic wavesbetween said ultrasonic sensor and said spherical-shaped float;directing a beam of light through the upper portion of said tubularcolumn, said beam of light when directed through the upper portion ofsaid tubular column providing an indication of a density for said foamwithin the upper portion of said tubular column; and generating a foamdensity indicating signal representative of the density of said foamwithin the upper portion of said tubular column.
 2. The method of claim1 further comprising the steps of: opening a drain valve located at thebottom of said tubular column; and deactivating said air valve whichdiverts said compressed gas from said aeration stone through a fluidpassageway to an opening within the upper portion of said tubular columnforcing said wastewater and said foam out of said tubular column throughsaid drain valve when said drain valve is open.
 3. The method of claim 2wherein a fourth of said plurality of control signals opens said drainvalve allowing said wastewater and said foam to drain from said tubularcolumn through said drain valve.
 4. The method of claim 1 wherein saidplurality of control signals are generated by a programmable logiccontroller.
 5. The method of claim 1 wherein said compressed gascomprises compressed air.
 6. The method of claim 1 further comprisingthe step of processing said analog signal and said foam densityindicating signal to generate an alarm signal.
 7. The method of claim 6wherein said alarm signal activates a red indicator light whenever saidspherical-shaped float rises above a predetermined set point within theupper portion of said tubular column.
 8. The method of claim 1 furthercomprising the step of removing oil from the sample of said wastewater.9. The method of claim 8 wherein a filter having an oleophilic elementremoves the oil from the sample of said wastewater.
 10. A method fordetecting and measuring foam in wastewater, comprising the steps of:generating a plurality of control signals, said plurality of controlsignals being generated by a programmable logic controller; introducinga sample of said wastewater through a fill valve into a verticallypositioned tubular column having an inner wall, a first of saidplurality of control signals opening said fill valve to allow saidwastewater to pass through said fill valve into said tubular column andflow down the inner wall of said tubular column to a lower portion ofsaid tubular column; generating a compressed gas, said compressed gasbeing generated by an electrically operated pump activated by a secondof said plurality of control signals; providing said compressed gasthrough an air valve to an aeration stone positioned in the lowerportion of said tubular column; generating air bubbles within saidwastewater causing a formation of said foam within said tubular column,said air bubbles being generated by air flow through said aeration stonewhen said compressed gas, responsive to a third of said plurality ofcontrol signals passes through said air valve to said aeration stone;raising a spherical-shaped float positioned within said tubular columnin an upward direction within said tubular column, said spherical-shapedfloat being raised within said tubular column by the formation of saidfoam within said tubular column; generating ultrasonic waves, saidultrasonic waves being generated by an ultrasonic sensor positioned atthe top of said tubular column; measuring a time of travel for saidultrasonic waves between said ultrasonic sensor and saidspherical-shaped float by bouncing said ultrasonic waves off of saidspherical-shaped float; generating an analog signal which is a functionof foam height within an upper portion of said tubular column, saidultrasonic sensor generating said analog signal in response tocontinuous measurement of the time of travel of said ultrasonic wavesbetween said ultrasonic sensor and said spherical-shaped float;directing a beam of light through the upper portion of said tubularcolumn, said beam of light when directed through the upper portion ofsaid tubular column providing an indication of a density for said foamwithin the upper portion of said tubular column; generating a foamdensity indicating signal representative of the density of said foamwithin the upper portion of said tubular column; opening a drain valvelocated at the bottom of said tubular column; and deactivating said airvalve which diverts said compressed gas from said aeration stone througha fluid passageway to an opening within the upper portion of saidtubular column forcing said wastewater and said foam out of said tubularcolumn through said drain valve when said drain valve is open, a fourthof said plurality of control signals opening said drain valve allowingsaid wastewater and said foam to drain from said tubular column throughsaid drain valve.
 11. The method of claim 10 wherein a pair ofphoto-optical sensors positioned in alignment on opposite sides of theupper portion of said tubular column measures the density of said foamwithin the upper portion of said tubular column, said pair ofphoto-optical sensors generating said foam density indicating signalrepresentative of the density of said foam within the upper portion ofsaid tubular column.
 12. The method of claim 11 wherein said compressedgas comprises compressed air.
 13. The method of claim 10 furthercomprising the step of processing said analog signal and said foamdensity indicating signal to generate an alarm signal, said alarm signalactivating a red indicator light whenever said spherical-shaped floatrises above a predetermined set point within the upper portion of saidtubular column.
 14. The method of claim 11 further comprising the stepof removing oil from the sample of said wastewater, wherein a filterhaving an oleophilic element removes the oil from the sample of saidwastewater.
 15. A method for detecting and measuring foam in wastewater,comprising the steps of: generating a plurality of control signals, saidplurality of control signals being generated by a programmable logiccontroller; introducing a sample of said wastewater through a fill valveinto a vertically positioned tubular column having an inner wall, afirst of said plurality of control signals opening said fill valve toallow said wastewater to pass through said fill valve into said tubularcolumn and flow down the inner wall of said tubular column to a lowerportion of said tubular column; generating a compressed gas, saidcompressed gas being generated by an electrically operated pumpactivated by a second of said plurality of control signals; providingsaid compressed gas through an air valve to an aeration stone positionedin the lower portion of said tubular column; generating air bubbleswithin said wastewater causing a formation of said foam within saidtubular column, said air bubbles being generated by air flow throughsaid aeration stone when said compressed gas, responsive to a third ofsaid plurality of control signals passes through said air valve to saidaeration stone; raising a spherical-shaped float positioned within saidtubular column in an upward direction within said tubular column, saidspherical-shaped float being raised within said tubular column by theformation of said foam within said tubular column; generating ultrasonicwaves, said ultrasonic waves being generated by an ultrasonic sensorpositioned at the top of said tubular column; measuring a time of travelfor said ultrasonic waves between said ultrasonic sensor and saidspherical-shaped float by bouncing said ultrasonic waves off of saidspherical-shaped float; generating an analog signal which is a functionof foam height within an upper portion of said tubular column, saidultrasonic sensor generating said analog signal in response tocontinuous measurement of the time of travel of said ultrasonic wavesbetween said ultrasonic sensor and said spherical-shaped float;directing a beam of light through the upper portion of said tubularcolumn, said beam of light when directed through the upper portion ofsaid tubular column providing an indication of a density for said foamwithin the upper portion of said tubular column, wherein a pair ofphoto-optical sensors positioned in alignment on opposite sides of theupper portion of said tubular column measures the density of said foamwithin the upper portion of said tubular column, said pair ofphoto-optical sensors generating said foam density indicating signalrepresentative of the density of said foam within the upper portion ofsaid tubular column; generating a foam density indicating signalrepresentative of the density of said foam within the upper portion ofsaid tubular column, wherein one of said pair of photo-optical sensorsgenerates said foam density indicating signal representative of thedensity of said foam within the upper portion of said tubular column;opening a drain valve located at the bottom of said tubular column; anddeactivating said air valve which diverts said compressed gas from saidaeration stone through a fluid passageway to an opening within the upperportion of said tubular column forcing said wastewater and said foam outof said tubular column through said drain valve when said drain valve isopen, a fourth of said plurality of control signals opening said drainvalve allowing said wastewater and said foam to drain from said tubularcolumn through said drain valve.
 16. The method of claim 15 wherein saidcompressed gas comprises compressed air.
 17. The method of claim 15further comprising the step of processing said analog signal and saidfoam density indicating signal to generate an alarm signal, said alarmsignal activating a red indicator light whenever said spherical-shapedfloat rises above a predetermined set point within the upper portion ofsaid tubular column.
 18. The method of claim 15 further comprising thestep of removing oil from the sample of said wastewater, wherein afilter having an oleophilic element removes the oil from the sample ofsaid wastewater.